Here is a project - "No Warranty Void" hack for the Scribbler and the S2. I call it the Scribbler Taillight. I was playing with the idea for following purposes. This could work great for LED scribbling too. I am developing a pen port mount also.
Power (9 volts) and ground come right from the programming port - not case opening is required for this hack (and thus your Warranty remains! ;-)
Photos show the following:
How an LED is fitted with pin connectors. Under the heat-shrink wrap around the Ground Leg (cathode - marked by the flat spot on the LED lense) is a resistor of the appropriate size for 9 volts and the color of the LED and its properties (Google it!) - two views. You can see the resistor under the black heat-shrink tubing.
Diagram for programming port pinout from Parallax (S2 and Scribbler are the same)
Diagram for a DB9 female pinout (show how the pins are numbered). This is marked to reflect the Scribbler and S2 power and ground. Pin 5 is ground and Pin 8 is 9 volts.
And photos of the Scribbler Taillight inserted - LED off and on.
Obviously the LED could be pointed straight up for LED scribbling, or mounted in the pen port and powered in the same way.
Give it try and have some hacking fun!